The invention relates to web spooling machinery running at high velocity and including devices for the automatic changeover from a filled-up spool to an empty one. The web spooling machinery to which this invention relates also includes a mechanism for severing the web and for guiding the severed end of the web onto the empty spool to continue the wind-up process thereon.
A machine of the above-described type has been proposed in which a reversing roller is associated with a pivotable knife which may be pivoted by an energy source acting through a gear train. The disposition of the severing knife on the shaft of the reversing roller causes the device to occupy only a small volume while the use of an energy storage mechanism for driving the pivotable knife imparts thereto a very high starting velocity and thus a very rapid severing speed. The severing speed may be as much as twice as great as the transport velocity of the web so that very sensitive webs running at high velocity, for example thin polyester foils for recording tapes, may be severed perpendicularly to the direction of motion of the web without any bunching or folding and may be securely attached to the new empty spool without requiring the use of adhesives.
In the practical application of the above-described known apparatus it has been demonstrated that it is only suitable for perpendicular severing of webs of foil which are no thicker than 0.05 millimeters and furthermore are capable of sustaining a relatively high tensile stress during the cutting. If the material is any thicker than 0.05 millimeters, the severing knife is no longer capable to make a clean cut as soon as it encounters the foil but, instead, the foil moves away from the knife to a greater or lesser degree so that no cut can take place or can take place only so far away from the intended position at which the end of the web may securely attach to the empty spool that it can no longer be smoothly attached to the spool without the creation of a fold-over.